Determination of vulnerability of essential genes in Pseudomonas aeruginosa using CRISPR interference (CRISPRi)
Metabolism, Biochemistry and Genetics of Microorganisms
Final Report Abstract
The type 6 secretion system (T6SS) is a nanomachine encoded by many Gram-negative bacteria used for warfare among different species to create a growth advantage in densely occupied niches. Some species, like Vibrio cholerae, use their T6SS in an untargeted fashion and seemingly fire randomly at other bacteria. In contrast, Pseudomonas aeruginosa use their T6SS more defensively, meaning that they only fire their T6SS when they have been challenged before. Interestingly, P. aeruginosa seems to sense the exact position of an incoming attack, because it is able to retaliate at the same position. However, the signal that is sensed by P. aeruginosa has not been identified to date. Here, we use a CRISPR interference approach to knockdown essential genes in the inner membrane, periplasm or outer membrane to interrogate whether membrane disruption is the signal that is sensed by P. aeruginosa. Indeed, knockdown of bamA, tolB and lptD led to increased functional T6SS activity and results in untargeted killing of T6-negative V. cholerae. Here, we show that outer membrane perturbation is sensed by P. aeruginosa and results in building of a functional T6SS apparatus.
